Linking microbial community composition to hydrogeochemistry in the western Hetao Basin: Potential importance of ammonium as an electron donor during arsenic mobilization

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  • External authors:
  • Wei Xiu
  • Jonathan Lloyd
  • Huaming Guo
  • Wei Dai
  • Cui Ren
  • Chaoran Zhang
  • Tiantian Ke

Abstract

Various functional groups of microorganisms and related biogeochemical processes are likely to control arsenic (As) mobilization in groundwater systems. However, spatially-dependent correlations between microbial community composition and geochemical zonation along groundwater flow paths are not fully understood, especially with respect to arsenic mobility. The western Hetao Basin was selected as the study area to address this limitation, where groundwater flows from a proximal fan (geochemical-group I: low As, oxidizing), through a transition area (geochemical-group II: moderate As, moderately-reducing) and then to a flat plain (geochemical-group III: high As, reducing). High-throughput Illumina 16S rRNA gene sequencing showed that the microbial community structure in the proximal fan included bacteria affiliated with organic carbon degradation and nitrate-reduction or even nitrate-dependant Fe(II)-oxidation, mainly resulting in As immobilization. In contrast, for the flat plain, high As groundwater contained Fe(III)- and As(V)-reducing bacteria, consistent with current models on As mobilization driven via reductive dissolution of Fe(III)/As(V) mineral assemblages. However, Spearman correlations between hydrogeochemical data and microbial community compositions indicated that ammonium as a possible electron donor induced reduction of Fe oxide minerals, suggesting a wider range of metabolic pathways (including ammonium oxidation coupled with Fe(III) reduction) driving As mobilization in high As groundwater systems.

Bibliographical metadata

Original languageEnglish
Article number105489
Pages (from-to)105489
JournalEnvironment International
Volume136
Early online date24 Jan 2020
DOIs
Publication statusPublished - 1 Mar 2020